uiimage - 如何使 UIImage 符合 Codable？

Question

Swift 4 有 Codable这太棒了。但是UIImage默认情况下不符合它。我们怎么能做到这一点？

我试过 singleValueContainer和 unkeyedContainer

extension UIImage: Codable {
  // 'required' initializer must be declared directly in class 'UIImage' (not in an extension)
  public required init(from decoder: Decoder) throws {
    let container = try decoder.singleValueContainer()
    let data = try container.decode(Data.self)
    guard let image = UIImage(data: data) else {
      throw MyError.decodingFailed
    }

    // A non-failable initializer cannot delegate to failable initializer 'init(data:)' written with 'init?'
    self.init(data: data)
  }

  public func encode(to encoder: Encoder) throws {
    var container = encoder.singleValueContainer()
    guard let data = UIImagePNGRepresentation(self) else {
      return
    }

    try container.encode(data)
  }
}

我收到 2 个错误

“必需”初始化程序必须直接在类“UIImage”中声明(而不是在扩展中)

不可失败的初始化程序不能委托(delegate)给用“init?”编写的可失败初始化程序“init(data:)”

一种解决方法是使用包装器。但是还有其他方法吗？

Answer 1

最简单的方法就是让它 Data而不是 UIImage :

public struct SomeImage: Codable {

    public let photo: Data
    
    public init(photo: UIImage) {
        self.photo = photo.pngData()!
    }
}

反序列化图像:

UIImage(data: instanceOfSomeImage.photo)!